摘要
Brassinosteroids （BRs） are essential hormones for growth and development of plant. In rice, BRs regulate multiple developmental processes and affect many important traits such as height, leaf angle, fertility and seed filling. We identified brassinosteroid-regulated proteins in rice using proteomic approaches and performed functional analysis of some BR-regulated proteins by overexpression experiments. Using two-dimensional difference gel electrophoresis （2-D DIGE） followed by protein identification by mass spectrometry, we compared proteomic differences in the shoots and roots of the BR-insensitive mutant d61-4 and BR-deficient mutant brd1-3. We identified a large number of proteins differentially expressed in the mutants compared with wild type control. These include a glycine-rich RNA-binding protein （OsGRP1） and a DREPP2 protein, which showed reduced levels in the BR mutants. Overexpression of these two proteins partially suppressed the dwarf phenotype of the Arabidopsis BR-insensitive mutant bri1-5. In contrast to the reduced protein level, the RNA level of OsGRP1 was not significantly affected in the BR mutants or by BR treatment, suggesting BR regulation of OsGRP1 at the posttranslational level. This study identifies many BR-regulated proteins and demonstrates that OsGRP1 functions downstream in the BR signal transduction pathway to promote cell expansion.
Brassinosteroids （BRs） are essential hormones for growth and development of plant. In rice, BRs regulate multiple developmental processes and affect many important traits such as height, leaf angle, fertility and seed filling. We identified brassinosteroid-regulated proteins in rice using proteomic approaches and performed functional analysis of some BR-regulated proteins by overexpression experiments. Using two-dimensional difference gel electrophoresis （2-D DIGE） followed by protein identification by mass spectrometry, we compared proteomic differences in the shoots and roots of the BR-insensitive mutant d61-4 and BR-deficient mutant brd1-3. We identified a large number of proteins differentially expressed in the mutants compared with wild type control. These include a glycine-rich RNA-binding protein （OsGRP1） and a DREPP2 protein, which showed reduced levels in the BR mutants. Overexpression of these two proteins partially suppressed the dwarf phenotype of the Arabidopsis BR-insensitive mutant bri1-5. In contrast to the reduced protein level, the RNA level of OsGRP1 was not significantly affected in the BR mutants or by BR treatment, suggesting BR regulation of OsGRP1 at the posttranslational level. This study identifies many BR-regulated proteins and demonstrates that OsGRP1 functions downstream in the BR signal transduction pathway to promote cell expansion.
基金
supported by grants from US Department of Energy (DE-FG02-09ER15973)
National Science Foundation of China (30870207)
The UCSF Mass Spectrometry Facility (A.L. Burlingame, Director) was supported by the Biomedical Research Technology Program of the National Center for Research Resources, NIH NCRR P41RR001614, NIH NCRRRR015804, NIH NCRR P41RR019934 and RR012961
